Glass container comprising a glass bottom with improved properties

Abstract

A glass container is provided that includes a tube, a circular bottom, and a longitudinal axis. A curved glass heel extends from an outer end the bottom to the first end of the tube. The two-dimensional distance h(x,y) between a contact plane and the outer surface. The two-dimensional distance is measured in a direction parallel to the axis. The slope magnitude of the outer surface at the given position x,y is given by
√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}.
The 75% quantile of values that have been determined for the term
√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}×d1/h(xy).sub.delta
for all given positions x,y within a circular area having a radius of 0.4×d2/2 and that correspond to the centre is less than 4100 μm/mm. The adjacent positions x,y increase stepwise by 200 μm, and h(x,y).sub.delta=h(x,y).sub.max−h(x,y).sub.min, h(x,y).sub.max is a maximum value for h(x,y) and h(x,y).sub.min is a minimum value for h(x,y) being determined in that circular area.

Claims

1. A glass container, comprising: a glass tube having a first end, a second end, an outer diameter (d1), an inner diameter (d2), and a glass thickness (s1); a circular glass bottom that closes the glass tube at the first end, wherein the circular glass bottom comprises an inner surface directed to an inside of the glass tube and an outer surface directed to an outside of the glass tube; a longitudinal axis (L.sub.tube) that passes through a center of the glass tube and the circular glass bottom; a curved glass heel extending from an outer end the circular glass bottom to the first end of the glass tube; a two-dimensional distance h(x,y) between a contact plane and the outer surface, wherein the contact plane is the plane on which the glass tube rests, wherein the outer surface at a given position x,y, with x=0 and y=0 in the center of the circular glass bottom, wherein the two-dimensional distance is measured in a direction that is parallel to the longitudinal axis (L.sub.tube), wherein
√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)} is a slope magnitude of the outer surface at the given position x,y, wherein a 75% quantile of values that have been determined for the term
√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}×d1/h(xy).sub.delta for all given positions x,y within a circular area having a radius of 0.4×d2/2 and a center that corresponds to the center of the glass circular bottom is less than 4100 μm/mm, wherein adjacent positions x,y increase stepwise by 200 μm, and wherein h(x,y).sub.delta=h(x,y).sub.max−h(x,y).sub.min, h(x,y).sub.max is a maximum value for h(x,y) and h(x,y).sub.min is a minimum value for h(x,y) being determined in that circular area.

2. The glass container of claim 1, wherein the 75% quantile of the values that have been determined for the term
√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}×d1/h(xy).sub.delta is less than 3900 μm/mm.

3. The glass container of claim 1, wherein the 75% quantile of the values that have been determined for the term
√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}×d1/h(xy).sub.delta is less than 3500 μm/mm.

4. The glass container of claim 1, wherein the radius is 0.6×d2/2.

5. The glass container of claim 4, wherein the 75% quantile of the values that have been determined for the term
√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}×d1/h(xy).sub.delta is less than 3900 μm/mm.

6. The glass container of claim 4, wherein the 75% quantile of the values that have been determined for the term
√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}×d1/h(xy).sub.delta is less than 3500 μm/mm.

7. The glass container of claim 1, wherein the radius is 0.8×d2/2.

8. The glass container of claim 7, wherein the 75% quantile of the values that have been determined for the term
√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}×d1/h(xy).sub.delta is less than 3900 μm/mm.

9. The glass container of claim 7, wherein the 75% quantile of the values that have been determined for the term
√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}×d1/h(xy).sub.delta is less than 3500 μm/mm.

10. The glass container of claim 1, wherein for a wavefront distortion W(,φ) of a laser light with a wave length of 520 nm, a beam width of at least 0.6×d2 and less than 0.85×d2, that passes through the circular glass bottom in a direction from the outer surface to the inner surface, that is aligned collinear with the longitudinal axis (L.sub.tube), and that has been corrected for piston, tilt and defocus, a peak to valley difference
(W(,φ).sub.corrected).sub.max−(W(,φ).sub.corrected).sub.min is less than 100 waves.

11. The glass container of claim 10, wherein the peak to valley difference is less than 40 waves.

12. The glass container of claim 1, wherein for a wavefront distortion W(,φ) of a laser light with a wave length of 520 nm, a beam width of at least 0.6×d2 and less than 0.85×d2, that passes through the circular glass bottom in a direction from the outer surface to the inner surface, that is aligned collinear with the longitudinal axis (L.sub.tube), and that has been corrected for piston and tilt, the corrected wavefront distortion is point symmetric and wherein for a fixed set of radii .sub.0=¼, .sub.0=½ and .sub.0=1, a azimuthal peak to valley difference
(W(,φ).sub.corrected).sub.max−(W(,φ).sub.corrected).sub.min is less than 100 waves.

13. The glass container of claim 12, wherein the azimuthal peak to valley difference is less than 40 waves.

14. The glass container of claim 1, wherein the outer surface of the circular glass bottom has a topography is defined by a function ĥ(x), wherein ĥ (x) is an azimuthal average of a distance between the contact plane and the outer surface at any given position that is located on a circle having a center that corresponds to the center of the circular glass bottom and the radius |x|, wherein individual values ĥ for ĥ (x) are determined for a plurality of circles the radius of which increases stepwise by 500 μm, starting with a circle around the center having a radius of 500 μm, wherein the individual values ĥ are determined in a range from x=−0.4×d2/2 to x=+0.4×d2/2, d2 having a size such that at least 4 values ĥ are determined, wherein the individual values ĥ can be fitted in a least square fit with a curvature function $\hat{h}\left(x\right)=\frac{-c\times x^2}{1+\sqrt{1-c^2\times x^2}}+h_0$ wherein c and h.sub.0are free fitting parameters, and wherein Δc is the standard deviation error for constant c when fitting the individual values ĥ(x) with the curvature function and wherein the relative standard deviation error Δc/c is less than 0.1.

15. The glass container of claim 14, wherein the individual values h have been determined in a range from x=−0.6×d2/2 to x=+0.6×d2/2 and the relative standard deviation error Δc/c is less than 0.1.

16. The glass container of claim 14, wherein the individual values ĥ have been determined in a range from x=−0.8×d2/2 to x=+0.8×d2/2 and the relative standard deviation error Δc/c is less than 0.1.

17. The glass container of claim 1, wherein for any cut surface of the circular glass bottom that is obtainable by cutting the circular glass bottom in a plane that includes the longitudinal axis (L.sub.tube) a condition is fulfilled that comprises:
s2.sub.max/s1×(s2.sub.max/s2.sub.min−1)≤1.1 wherein s2.sub.max corresponds to a maximum glass thickness of the circular glass bottom, wherein s2.sub.min corresponds to a minimum glass thickness of the circular glass bottom, wherein s2.sub.max and s2.sub.min are determined within a given cut surface within the range from x=−0.4×d2/2 to x=+0.4×d2/2, and wherein s2.sub.min and s2.sub.max are both measured in a direction that is parallel to the longitudinal axis (L.sub.tube).

18. The glass container of claim 17, wherein s2.sub.max and s2.sub.min are determined within a given cut surface at least within the range from x=−0.6×d2/2 to x=+0.6×d2/2.

19. The glass container of claim 17, wherein s2.sub.max and s2.sub.min are determined within a given cut surface at least within the range from x=−0.8×d2/2 to x=+0.8 X d2/2.

20. The glass container of claim 1, wherein the glass container comprises a pharmaceutical composition.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a cross-sectional view of a glass container according to the invention, wherein for the purpose of an improved illustration the parts of the glass container (i. e. glass tube 101, glass bottom 104 and curved glass heel 107) have been separated from each other;

(2) FIG. 2 shows a cross-sectional view of a glass container 100 according to the invention in which the individual container parts shown in FIG. 1 (i. e. glass tube 101, glass bottom 104 and curved glass heel 105) are arranged in the usual way;

(3) FIGS. 3A-C show a cross-sectional view of the bottom area of a glass container 100 according to the invention and illustrate the different areas in which individual values for ĥ or ĥ(x) can be determined;

(4) FIGS. 4A-4B show the arrangement of concentrical circles 111 along which the individual values for ĥ are determined (FIG. 4A) and the way in which the azimuthal average for ĥ is obtained for a given circle 111 (FIG. 4B);

(5) FIG. 5 shows a graph of the individual values for ĥ that have been determined for a given circular glass bottom 104 and the fitted function ĥ (x) (dashed line);

(6) FIGS. 6A-B show the experimental setup that has been used to determine the two-dimensional distance h(x,y) and the slope magnitude of the outer surface of the glass bottom at a given position x,y;

(7) FIGS. 7A-B show in a side view the localization of plane 113 that is used to determine s2.sub.max and s2.sub.min in the circular glass bottom 104 of the glass container 100 (FIG. 7A) and the localization of s2.sub.max and s2.sub.min as well as the width of the area within which these values are to be determined in an exemplary bottom cross-section (FIG. 7B);

(8) FIGS. 8A-8D show the process for the preparation of a glass container 100 according to the present invention;

(9) FIG. 9 shows the movement of the separation gas burners 120 and the lower clamping chucks 119 at the time at which the lower clamping chucks 119 are moved downwards;

(10) FIG. 10 shows the experimental set up for the characterization of wavefront distortions caused by the outer contour of the circular glass bottom 104;

(11) FIGS. 11A-C show the simulation results for the passage of an image through a distorted glass bottom 104.

DETAILED DESCRIPTION

(12) FIG. 1 shows a cross-sectional view of a glass container according to the invention, wherein for the purpose of an improved illustration the parts of the glass container (i. e. glass tube 101, glass bottom 104 and curved glass heel 107) have been separated from each other. The glass container 100 comprises a glass tube 101 with a first end 102 and a further end 103, the glass tube 101 having an outer diameter d1, an inner diameter d2 and a wall thickness s1. The glass tube 101 is further characterized by a longitudinal axis L.sub.tube that passes through the centre of the first end 102 and the further end 103. The glass tube further comprises a circular glass bottom 104, wherein the circular glass bottom 104 closes the glass tube 101 at the first end 102, wherein the circular glass bottom 104 comprises an inner surface 105 directed to the inside of the glass container 100, an outer surface 106 directed to the outside of the glass container 100 and a centre 110. The glass container further comprises a curved glass heel 107 extending from an outer end 108 of the circular glass bottom 104 to the first end 102 of the glass tube 101. As can also be seen in FIG. 1, the glass bottom is preferably characterized by a bottom indentation t which usually takes on the maximum value in the centre 110 of the circular glass bottom 104. FIG. 2 shows a glass container 100 in which the individual container parts shown in FIG. 1 (i. e. glass tube 101, glass bottom 104 and curved glass heel 107) are arranged in the usual way.

(13) FIG. 3A, 3B and 3C show a cross-sectional view of the bottom area of a glass container 100 according to the invention and illustrate the different areas (x±0.4×d2/2 in FIG. 3A, x±0.6×d2/2 in FIG. 3B and x±0.8×d2/2 in FIG. 3C) in which the distance h between a contact plane 109 and the outer surface 106 of the circular glass bottom 104 at a given position x, with x=0 in the centre 110 of the circular glass bottom 104, is determined. The individual values of h can be applied to determine ĥ and ĥ(x).

(14) FIG. 4A shows the arrangement of concentrical circles 111 along which the individual values for ĥ are determined. As shown in FIG. 4B, for the determination of the individual values for ĥ, for any given circle the distance h between contact plane 109 representing the ground on which the glass container 100 rests and the outer surface 106 of the circular glass bottom 104 is determined in regularly steps of 5° (i. e. 72 measuring points per circle; for the sake of clarity only 5 steps are shown in FIG. 4B), serving as data points for an azimuthal average. The first circle 111 is a circle having a diameter of 500 μm and the radius increases for the following circles stepwise by 500 μm (which means that the radius of the second circle is 1,000 μm, the radius of the third circle is 1,500 μm and so on).

(15) From the thus obtained values for h the azimuthal average corresponds to the individual value ĥ that has been determined for any given circle 111. FIG. 5 shows a graph of the individual values for ĥ that have been determined for a given circular glass bottom 104 and the fitted function ĥ(x) (see the dashed line). The fitted function is represented by formula (I)

(16) $\begin{array}{cc}\hat{h}\left(x\right)=\frac{-c\times x^2}{1+\sqrt{1-c^2\times x^2}}+h_0& \left(I\right)\end{array}$

(17) in which c and h.sub.0 serve as individual fitting parameters. The above function is the curvature function of a sphere having the radius R with c=1/R. Values for c (and also for the standard deviation error (Δc) indicating how exactly the determined individual values of ĥ can be reproduced using the curvature function given above) are determined using an appropriate mathematical software (ASCAN-Software) as described in the “Test method”-section above.

(18) FIGS. 6A and 6B show the experimental setup that has been used to determine the two-dimensional distance h(x,y) and the slope magnitude
√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}

(19) of the outer surface 106 of the glass bottom 104 at a given position x,y. The distance h(x,y) between the outer surface 106 of the circular glass bottom 104 and the ground at a given position x,y is determined by means of a non-contact profilometer. For the determination of the individual values of the two-dimensional distance h(x,y), the glass bottom 104 is divided into an array of square parts 112 having an edge length of 200 μm. At the centre of each of these square parts 112 the distance between the outer surface 106 of the glass bottom 104 and the ground is determined at measurement point 135 as shown in FIG. 6A (the individual measurement points 135 are evaluated in an order following the arrows shown in FIG. 6A) and addressed to the corresponding x and y values of the respective square and stored as an individual value of h(x,y). From the thus obtained values for the two-dimensional distance h(x,y) only those values are selected for calculating the slope magnitude and for determining h(x).sub.max and h(x).sub.min that have been obtained for measurement points 135 that are located within a circular area 136 having a radius of 0.4×d2/2 (or within a circular area 137 having a radius of 0.6×d2/2 or within a circular area 138 having 0.8×d2/2) as shown in FIG. 6A.

(20) From the thus obtained h(x,y)-values the slope magnitude representing the slope of between measurement points for different x and y, preferably between neighboring measurement points, is calculated using an appropriate mathematical software, for example the “Slope Analysis” function of the Mx software.

(21) The h(x,y).sub.max-value corresponds to the highest h(x,y)-value and the h(x,y).sub.min-value corresponds to the lowest h(x,y)-value that have been determined within the circular area 136 having a radius of 0.4×d2/2 (or within the circular area 137 having a radius of 0.6×d2/2 or within the circular area 138 having a radius of 0.8×d2/2).

(22) FIG. 7A shows in a side view the localization of plane 113 that is used to determine s2.sub.max and s2.sub.min in the bottom 104 of the glass container 100. Plane 113 corresponds to the plane that is centrically located in the glass container 100 and that comprises the longitudinal axis L.sub.tube of the glass container 100 (indicated by the dashed line in FIG. 7A), i. e. the axis that goes perpendicular through the centre 110 of the bottom 104 (see FIG. 7B). FIG. 7B shows the localization of s2.sub.max and s2.sub.min as well as the width of the area within which these values are to be determined in an exemplary bottom cross-section. As can be seen, s2.sub.max and s2.sub.min are determined within an area that extends over about 65% of the area of the circular glass bottom, wherein the centre of this area is located in the centre 110 of the circular glass bottom 104.

(23) FIGS. 8A-D show the process for the preparation of a glass container 100 that displays a glass bottom as define herein. In a first process step I) the glass tube 101 having an upper portion 116 with an upper end 117 and a lower portion 114 with a lower end 115 is held by means of upper and lower clamping chucks 118,119 in a vertical position. The glass tube 101 is heated at a defined position between the lower and the upper portion 114,116 by means of two opposed separation gas burners 120 to a temperature above the glass transition temperature while the glass tube 101 is rotating around its longitudinal axis L.sub.tube (see FIG. 8A). In process step II) the lower portion 114 of the glass tube 101 is pulled downwards by moving downwards the lower clamping chucks 119 while the glass tube 101 is rotating around its longitudinal axis L.sub.tube (see FIG. 8B). When moving downwards the lower clamping chucks 119 and thus also the lower portion 114 of the glass tube 101, a glass thread 121 is formed (see also FIG. 8B). When further moving downwards the lower portion 114, this portion is separated from the upper portion 116 by pulling apart the glass thread 121, the part of the mass of the glass thread 121 that remains at the lower portion 114 of the glass tube 101 forming a circular bottom 104 (see FIGS. 8C and 8D). The process for the preparation of a glass container according to the present invention is characterized in that, while pulling downwards the lower portion 114, the at least one separation gas burner 120 does not remain at the same position as it is observed in the process known from the prior art, but is moved downwards in a direction that is substantially parallel to the direction in which the lower clamping chucks 119 are moved downwards (indicated by the arrows beneath the separation gas burners 120 in FIG. 8A), the at least one separation gas burner 120 thereby following the upper end 122 of the lower portion 114.

(24) FIG. 9 shows the movement of the separation gas burners 120 and the lower clamping chucks 119 at the time at which the lower clamping chucks 119 are moved downwards. In the embodiment of the process shown in FIG. 9, the lower clamping chucks 119 are moved downwards at a point of time t and the at least one separation gas burner 120 is moved downwards at a point of time t′=t+Δt, wherein Δt can be zero (which means that the lower clamping chucks 119 and the at least one separation gas burner 120 are moved downwards simultaneously) or Δt can be larger than zero. In this case the at least one separation gas burner 120 is moved downwards with a time delay in relation to the lower clamping chucks 119. As can also be seen in the embodiment of the process shown in FIG. 9, the at least one separation gas burner 120 is moved downwards starting from a position Y′.sub.0 to a position Y′.sub.stop and the lower clamping chucks 119 start from a position Y.sub.0 and, preferably after the at least one separation gas burner 120 has stopped at position Y′.sub.stop, to stop at a position Y.sub.stop, wherein |Y′.sub.stop−Y′.sub.0|<|Y.sub.stop−Y.sub.0|. According to this embodiment it is thus preferred that the distance with which the at least one separation gas burner 120 is moved downwards is smaller than the distance with which the lower clamping chucks 119 are moved downward.

(25) FIG. 10 shows the experimental setup to characterize wavefront distortions caused by the outer shape of the glass bottom 104 of a glass container 100 (which in FIG. 10 is a vial), independent of the imaging system eventually used for the inspection. A collimated laser beam 130 of 1/e.sup.2 diameter (2W=3 mm) and wavelength of 520 nm from a laser source 132 (e.g. Thorlabs PL201, in order to cover 70% of d2 for vial with d2=13 mm it has been extended to 2W=9 mm with the Beamexpander Thorlabs GBE01-A) is directed towards the glass bottom 104 of a vial 100 standing on a transparent support 128. Since the inspection is usually carried out with a filled vial 100, the vial 100 is filled with water 127 up to a height that completely covers the inner surface 105 of the glass bottom 104. Practically this can be achieved with a fill height of 10 mm. The effect of the inner surface 105 of the glass bottom 104 on the optical imaging can be neglected since n.sub.vial−n.sub.filling≈0.01<n.sub.vial−n.sub.air≈0.5, thus the inner surface 105 of the glass bottom 104 has a much smaller effect on the wavefront. However, in this measurement it is intended to completely eliminate the influence of the inner surface 105 of the glass bottom 104 and for that purpose an index-matching liquid of n=n.sub.vial is selected. One crucial factor of the measurement is the inner neck diameter d4 of the vial 100. In order to characterize the wavefront distortion for a laser diameter that is larger diameter than d.sub.4, the top region of the vial 100 is removed along a cutting plane 126. Thus, if no further imaging optic (e. g. another beam expander used in reverse) is used, the measurement aperture 124 of the Shack-Hartmann sensor 123 determines the diameter of the wavefront measurement. For the experimental set up used herein a Shack-Hartmann sensor 123 with a large aperture 124 of 11.26mm×11.26 mm has been used (WFS40-7AR, Thorlabs Inc.). Thus, in this setup it would be necessary to shrink the beam size with another beam expander, if vials with d.sub.2 larger than 13 mm are investigated.

(26) The Shack-Hartmann sensor 123 contains an array micro-lenses 133 that images a characteristic dot pattern onto a CCD. For a planar wavefront 129, the dot pattern has the same spacing as the spacing of the micro-lens array. However, if the wavefront is aberrated when passing through the glass bottom to obtain the aberrated wavefront 125, any aberrations locally displace the dot laterally in the direction of the distortion (as shown in FIG. 3 of the publication “History and Principles of Shack-Hartmann Wavefront Sensing”; Ben C. Platt and Roland Shack; Journal of Refractive Surgery; Vol. 17 (2001), pages S573-S577). This way, the distortion can be mapped onto the nodes W.sub.i the micro-lens array the Shack-Hartmann-Sensor 123 provides.

(27) FIGS. 11 A-C show the simulation results for the passage of an image through a distorted glass bottom 104. The form of the glass bottom 104 follows real measurements, which were obtained by measuring and averaging the height at several 500 μm spaced rings and fitting a spline function through all radial nodes (FIG. 11B, wherein the figure on the left represents the outer contour of a state-of-the-art glass bottom 104 and the figure on the right represents the outer contour of a glass bottom 104 in a glass container according to the present invention). An ideal objective of NA 0.5 is assumed for the vial 100 (filled with 20 mm of water). The effect of the inner surface 105 of the vial bottom 104 has been neglected. While the optical power caused by the curvature of the vial bottom can be easily corrected by shifting the image plane (so called defocus correction), higher order aberrations cannot: The state-of-the-art glass bottom 104 significantly distorts the image and even after defocus correction, the image at the image plane 134 remains blurred due to spherical aberrations (see the figure on the left of FIG. 11C). The glass bottom 104 in the glass container 104 according to the present invention is less flat, but with significant lower radial variation. The image itself after defocus correction is only slightly perturbed (see FIG. 11C on the right) and is suitable for analysis, e.g. particle detection.

LIST OF REFERENCE NUMERALS

(28) 100 glass container

(29) 101 glass tube

(30) 102 first end of the glass tube 101

(31) 103 second end of the glass tube 101

(32) 104 circular glass bottom

(33) 105 inner surface of the circular glass bottom 104

(34) 106 outer surface of the circular glass bottom 104

(35) 107 curved glass heel

(36) 108 outer end of the circular glass bottom

(37) 109 contact plane representing the ground

(38) 110 centre of the glass bottom 104 or the circle 111

(39) 111 Circle

(40) 112 square in the centre of which h(x,y) is determined

(41) 113 cut surface

(42) 114 first or lower portion of the glass tube 101

(43) 115 first or lower end of the first or lower portion 114

(44) 116 second or upper portion of the glass tube 101

(45) 117 second or upper end of the second or upper portion 116

(46) 118 first or upper clamping chucks

(47) 119 second or lower clamping chucks

(48) 120 separation gas burner

(49) 121 glass thread

(50) 122 upper end of portion 114,116, preferably of lower portion 114

(51) 123 Shark-Hartmann-sensor

(52) 124 aperture for measuring range of the Shark-Hartmann-sensor 123

(53) 125 wavefront aberrated by the circular glass bottom 104

(54) 126 cutting plane if top region has to be removed for measurement

(55) 127 H.sub.2O (filling height: 10 mm)

(56) 128 transparent support

(57) 129 undisturbed wavefront

(58) 130 collimated laser beam (width: 1/e.sup.2 at 2W)

(59) 131 laser source (520 nm)

(60) 132 plane of object

(61) 133 lens (NA 0.5)

(62) 134 plane of image

(63) 135 measurement point

(64) 136 circular area having a radius of 0.4×d2/2

(65) 137 circular area having a radius of 0.6×d2/2

(66) 138 circular area having a radius of 0.8×d2/2